Transformation of direct currents.



P. AMSLER. TRANSFORMATION OF DIRECT UUBRENTS. APPLICATION FILED MAR. 29, 1912.

b Patented Dec. 10, 1912.

Pill/Z Ams Zer, 6 Z/Wm fi m l-..r1 z3ys ing to oneform of the invention.

UNITED PA EN O PAUL AMSLER,

or IBADENL, swrrznailinn. essrernon TO AKTIENGEsELLsgnAm BROWN BOVERI & cm, or annn, SWITZERLAND.

TRANSFORMATION OF DIRECT CURRENTS.

To all whom it may concern:

Be it known that I, PAUL AMsLnR, engineer, a citizen of the Republic of France, and residing at Baden, Switzerland, have invented certain new and useful Improve.- ments in and Relating to theTransforma tion of Direct Currents, of which the fol,- lowing is a specification.

This invention relates to the transformation of direct currents, particularly those of high tension.

lVith shunt excited direct current inachines for high tension it is necessary to use field windings consisting of a large number of fine wire coils which have ,to beinsulated for the high voltage, rendering the machines expensive and impairing their re liability.

I The object of the present invention is to provide a transforming. arrangement, particularly in' connection with such machines which will render them free of the disadvantages referred to above.

The invention in brief consists in me chanically coupling together a motor and a dynamo and exciting the motor by means of a series high tension Winding of substan tially few turns an opposing series low tension Winding-and a low tension winding of a comparatively large number of turns assisting the first winding.

The invention also consists in providing a main excitation for a high tension motor from a. source of low tension supply comprising a dynamo electric machine driven by the main motor, an additional winding being added so that starting can be effected solely by the high tension current.

The accompanying diagrams represent several examples of carrying the invention into effect.

Figure 1 shows a general scheme accord- 2 shows a modification which the" dynamo is provided with an extra field winding. Fig. 3 showsa form in which both dynamo and motorare combined in one machine.

In the form illustrated in Fig. 1, the. 1110- tor a to be driven by energy from high tension direct current mains b is mechanically coupled by the shaft 0 to the dynamo d which supplies energy to low tension mainse'. The motor a is provided with three field windings f, g and It, f being fed from the Specification of Letters Patent. Application filed March 29, 1912. Serial No. 687,215.

Patented Dec 10,1912.

high tension supply as a series winding and g a reverse or negative compound winding from the dynamo (i. The third winding h is a shunt winding fed from the dynamo d and acts to assist the winding f. A suitable shunt exciting winding 2' is provided for the dynamo d. 1 1

In operation by means of a switch is high tension current is supplied to the motor .a

and its field winding f. This causes starting of the motor with a. high torque, due to the series coils and effects rotation of the dynamo (Z. The winding 71. now begins to. become excited from this dynamo and toassist the winding f, first strengthening the series excitation and subsequently outgrowing the same. If power be now taken from the dynamo side it will cause mechanical power to be absorbed from the shaft 0 from the motor a, which in operation will draw more current from the high tension mains and will result in a stronger excitation of the motor field through the winding f. This would of itself reduce the speed of the motor, but the action is prevented by means of the reverse winding 9 carrying the load current of the dynamo, which reduces the exci-' tation of the motor field as the Winding f tends to increase it. By suitable design of these three field windings constancy of the dynamo E. M. F. can be obtained.

The form of the invention illustrated'in- Fig. 2 is similar to that shown in Fig. 1 and a second winding j is provided for the dynamo (Z in senes with the winding f to insure that the dynamo shall excite itself always and prevent racing of the motor m.

The windings j and t assist one another.

In. connection with l gh tension train lighting installation a. voltage of about 1500 may be employed which would-require thirteen 115 volt lamps in series. By transforming according to the present invention the lamps can all be used in parallel and in this connection it may he noted that the winding j introduces the further advantage that the lamps begin t'oglow immediately after the closing of the main switch is, since the set becomes excited very qui( .y with this arrangement.

The modification shown in Fig. 3 introduces a combined motor and dynamo with two commutatorscorresponding to the low tension dynamo and high tension motor respectively. in this case the winding 7" can replace the windings f and j of Fig. 2 and the Winding ]L can replace the windings 71, and 2' of the same figure.

Having now described my inveniion What I claim as new and desire to secure by Lettors Patent is:-

1. In an electric system having high tension mains, a motor fed thereby and e, dy- Ila-mo constructed to generate low tension currents, and having its armature mechanically connected to the armature of the motor, said motor having field coils composed of a series winding of comparatively few turns fed from the high tension mains,

an opposing low tension Winding in series With the dynamo, and a 10W tension Winding of a COHI OZLI'ELUVGiY large number of turns in shunt with the dynamo and in assisting relation to the first nainedjvincling.

2. In an electric system a motor and a dynamo having its :ri'n'ia ture mechanically connected i0 that of the motor for actuation thereby, said motor having field coils comprising a. winding in series with the motor armature, a Winding in series with the dynamo and a Winding in shunt with the dynamo, the first and second windings being in opposition, and the third Winding being in assisting relation to the first Winding.

In testimoiiy whereof, I eiiix my signa ture in presence oi. two Witnesses.

PAUL AMSLER. Witnesses CARL Gemini, AUGUST Rmhee. 

